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Let $R (a, b, c)$ and $S(d, e, f)$ be two relations in which $d$ is the foreign key of $S$ that refers to the primary key of $R$. Consider the following four operations $R$ and $S$

1. Insert into $R$

2. Insert into $S$

3. Delete from $R$

4. Delete from $S$

Which of the following can cause violation of the referential integrity constraint above?

1. Both I and IV

2. Both II and III

3. All of these

4. None of these

edited | 3.6k views
0
ans:-B

 a Let(PK) b c 1 2
 d(FK referring to PK of R) e f 2 1

Insert into R cannot cause any violation.

Insert into S can cause violation if any value is inserted into d of S, which value is not in a of R.

Delete from S would cause no violation.

Delete from R  would cause violation if  it any tuple is deleted,and as a result a value in a gets deleted which is refereed to by d in S.

answered by Active (3.6k points)
edited
0
This question build my referential integrity constraint concept very well
2-Insert into S   and  3-Delete from R  ,can cause Violation of the Referential integrity constraints.

Hence ,ans  is  (B) Both II and III
answered by Loyal (7.2k points)

Delete from S– Can cause violation if we delete any value of x in S, then the value referred by in R should also be deleted.

Insert into R- When we will insert any value in R it will not in S so cause the violation.

answered by (453 points)

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